immobilization of arsenic in mine tailings using standard and nanoscale metal oxides

107 Pages·2011·2.03 MB·English

IMMOBILIZATION OF ARSENIC IN MINE
TAILINGS USING STANDARD AND NANOSCALE
METAL OXIDES

Sevag Derghazarian

A Thesis
In
The Department
of
Building, Civil and Environmental Engineering

Presented in Partial Fulfillment of the Requirements
for the Degree of Master of Applied Science (Civil Engineering) at
Concordia University
Montreal, Quebec, Canada

November 2010

© Sevag Derghazarian, 2010
CONCORDIA UNIVERSITY
School of Graduate Studies

This is to certify that the thesis prepared

By: Sevag Derghazarian

Entitled: IMMOBILIZATION OF ARSENIC IN MINE TAILINGS USING STANDARD AND
NANOSCALE METAL OXIDES

and submitted in partial fulfillment of the requirements for the degree of

Master of Applied Science (Civil Engineering)

complies with the regulations of the University and meets the accepted standards with
respect to originality and quality.

Signed by the final examining committee:

Dr. R. Zmeureanu Chair

Dr. G. DeWolf External Examiner

Dr. S. Li Examiner

Dr. C. Mulligan Supervisor

Approved by Dr. K. Ha-Huy, GPD o
Chair of Department or Graduate Program Director

Dr. R. Drew 0
Dean of Faculty

Date January 11 2011 0
ABSTRACT

IMMOBILIZATION OF ARSENIC IN MINE TAILINGS USING STANDARD AND
NANOSCALE METAL OXIDES
Sevag Derghazarian

Elevated levels of arsenic can be found in mine tailings, sediment and soil samples.
Leaching of arsenic from tailings can lead to the contamination of surface and
groundwater. One potentially sustainable method is to add various agents to stabilize the
waste and ensure that arsenic does not leach out of the waste. In the current study, the
effectiveness of various types of metal oxides as immobilizing agents was tested.
Leaching tests and SSE (Selective Sequential Extraction) were performed on different
mixtures of mine tailings and metal oxides, using different weight ratios, reaction times,
types of oxides. The mine tailings were taken from different sites in Canada.
The metal oxides used were either regular (commercial grade) or nanoscale powders. The
additives evaluated were MgO, ZnO, Fe O , TiO , CaO and Al O . These additives were
3 4 2 2 3
chosen for their successful use as commercial agents in chemical decontamination. The
leaching tests were done using a solution of distilled water and sulphuric acid at a pH of 3
to simulate acid rain fall on the mine tailings that could occur. The concentration of
arsenic in the leachate was measured using arsenic test kits and ICP-MS instrumentation.
It was found that both regular and nanoscale ZnO (zinc oxide) had the highest capacity to
immobilize the arsenic present in the mine tailings, whereas the other metal oxides tested
and Fe O (magnetite) had little or no effect. Leaching tests performed on Noranda and
3 4
Golden Giant mine tailings over a 24 hour period revealed that the addition of 7.5% in
weight of nanoscale ZnO caused a 99.4% to 99.7% reduction in the amount of arsenic
leached into solution of distilled water at a pH of 3. A 91% to 92% reduction was
observed when the additives were left to immobilize the tailings for a period of 1 month.
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SSE tests confirmed that ZnO is a very effective immobilizing agent in all of the five
chemical phases and stable on a long-term basis. SSE tests showed a reduction in the
amount of arsenic leached by a factor of more than 31 in the exchangeable phase, and by
a factor of 4.9 in the water soluble phase, and 5.1 in the carbonate phase for Noranda
mine tailings treated with 7.5% regular grade ZnO. Leaching from each of the other
phases was also minimized. These results indicate the possibility of developing a
sustainable remediation process for mining areas as well as other contaminated soil using
ZnO. Further studies on immobilization are recommended using ZnO in conjunction with
other metal oxides or compounds that would improve efficiency, reduce costs and
minimize the leaching of zinc into the soil.

iv
ACKNOWLEDGMENTS

I would like to thank many people who helped me in the completion of this thesis.
My first acknowledgement goes to my supervisor Dr. Mulligan who accepted to take
me as her student to begin with, then skilfully guided me until the completion of my
work. She provided me with all the necessary support and guidance, whether
financial or academic, and encouraged me to think independently and be
autonomous. I am also grateful to Claire Therrien who has been so helpful in the
laboratory to answer any questions I had and to guide me and help me in time of
need.
I am grateful to all my fellow Master’s and PhD students for their continuous support
and help in all aspects of my experimental and thesis work. They have been there for
me through all circumstances. Mahmood deserves a special appreciation for his
tireless support in the lab at all times and all hours. Inoue, Mohamed, Farnaz, Zaid,
Dima, Rifat, Azita, Azadeh, Theju, Rashed and Ali have also been available for me.
I also acknowledge the contribution of the Department of Building, Civil and
Environmental Engineering of Concordia and the University itself for giving me the
ability to undertake this program.
Last but not least, all my friends and family deserve alot of appreciation. I would like
to thank my mother Barbara, father Chahé, my siblings Alec, Sandra and Tamar, my
grandmother Nevart and all my other aunts, uncles and cousins for their direct and
indirect support. Finally I would like to thank all my friends Ralph, Antoine, Pamela,
Anna, Lucie, Harshad and Samer. Special thanks goes to Sudha who guided me with
her expertise and knowledge.
It is my sincere wish that this work be of use to the environment and help in our
ongoing battle against arsenic poisoning across the world.

v
TABLE OF CONTENTS
LIST OF FIGURES .................................................................................................................................................. viii
LIST OF TABLES ....................................................................................................................................................... x
NOMENCLATURE ................................................................................................................................................... xi
1 INTRODUCTION ............................................................................................................................................. 1
1.1 STATEMENT OF PURPOSE .................................................................................................................................... 1
1.2 OBJECTIVES ..................................................................................................................................................... 3
1.3 PLAN OF THESIS ................................................................................................................................................ 3
2 LITERATURE REVIEW ...................................................................................................................................... 5
2.1 ARSENIC - AN OVERVIEW ................................................................................................................................... 5
2.2 ARSENIC SOURCES IN CANADA ............................................................................................................................. 6
2.3 MINE TAILINGS – HISTORY AND ORIGIN................................................................................................................. 8
2.4 ARSENIC IN MINE TAILINGS, SOILS AND SEDIMENTS ................................................................................................ 10
2.5 REMEDIATION METHODS FOR CONTAMINATED SOILS ............................................................................................ 12
2.6 IMMOBILIZATION OF ARSENIC ............................................................................................................................ 18
2.7 GENERAL ADSORBENTS USED FOR REMOVAL OF ARSENIC ......................................................................................... 23
3 MATERIALS AND METHODS ......................................................................................................................... 28
3.1 CHARACTERIZATION OF MINE TAILINGS USING XRF .............................................................................................. 28
3.2 PREPARATION OF SAMPLES FOR ANALYSIS ............................................................................................................ 29
3.3 LEACHING AND EXTRACTION TESTS ..................................................................................................................... 29
3.3.1 Immobilization of mine tailings ............................................................................................................. 29
3.3.2 Preliminary Leaching tests ..................................................................................................................... 29
3.3.3 Selective Sequential Extraction (SSE ) tests............................................................................................ 33
3.4 ANALYTICAL METHODS .................................................................................................................................... 37
3.4.1 Hach EZ Arsenic Test Kits ....................................................................................................................... 37
3.4.2 ICP-MS ................................................................................................................................................... 39
3.4.3 Hydride Generation Atomic Absorption Spectrometry (HG-AAS) .......................................................... 40
3.4.4 Flame Atomic Adsorption (FAAS) ........................................................................................................... 41
4 RESULTS AND DISCUSSION ........................................................................................................................... 43
4.1 CHARACTERIZATION OF MINE TAILINGS USING XRF ............................................................................................... 43
4.2 LEACHING TESTS ............................................................................................................................................. 45
4.2.1 Effect of Type of Metal Oxide Additives on Arsenic Immobilization at a fixed 10% weight
additive/ weight tailing ratio .............................................................................................................................. 46
4.2.2 Effect of Weight Additive/ Weight Tailing ratio on Arsenic Immobilization for two metal oxide
additives over a period of 24 hours .................................................................................................................... 49
4.2.3 Effect of Weight Additive/ Weight Tailing ratio on Arsenic Immobilization for two metal oxide
additives over a period of 1 month ..................................................................................................................... 54
4.2.4 Concentration of Zinc Ions in Solution ................................................................................................... 57
4.3 SSE TESTS ..................................................................................................................................................... 59
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4.3.1 SSE Tests on ZnO Additives and Noranda Mine Tailings ........................................................................ 59
4.3.2 SSE Tests on ZnO Additives and Golden Giant Mine Tailings ................................................................. 65
4.3.3 SSE Tests on Fe O Additives and Noranda Mine Tailings ..................................................................... 69
3 4
4.3.4 SSE Tests on Fe O Additives and Golden Giant Tailings ....................................................................... 73
3 4
4.3.5 Discussion on the immobilization mechanisms of ZnO additives........................................................... 79
4.4 DISCUSSION ON THE PERFORMANCE OF FE3O4 ...................................................................................................... 81
4.5 SUMMARY OF RESULTS .................................................................................................................................... 83
5 CONCLUSIONS AND RECOMMENDATIONS ................................................................................................... 85
5.1 SUMMARY AND CONCLUDING REMARKS .............................................................................................................. 85
5.2 RECOMMENDATIONS FOR FUTURE WORK ............................................................................................................. 87
6 REFERENCES ................................................................................................................................................. 89

vii
LIST OF FIGURES
Figure 2-1 Several steps in the vitrification procedure for metal, which includes: 1) Insertion of
electrodes, graphite and glass frit starter path to start vitrification, 2) Soil subsidence due to
vitrification 3) Placing of a backfill over vitrified monolith (Mulligan et al., 2001) .................................... 13
Figure 4-1 Arsenic concentration (ppb) leached from Noranda mine tailings according to type of
metal oxide additive. Results were measured using Hach EZ Arsenic tests strips. .................................... 47
Figure 4-2 Arsenic concentration (ppb) leached from Golden Giant mine tailings according to
type of metal oxide additive. Results were measured using Hach EZ Arsenic test strips. ......................... 48
Figure 4-3 % Arsenic leached according to type of metal oxide additive, in comparison to plain
Noranda mine tailings. Results were measured using ICP-MS. .................................................................. 48
Figure 4-4 % Arsenic leached according to type of metal oxide additive, in comparison to plain
Noranda mine tailings. Results were measured using ICP-MS. .................................................................. 49
Figure 4-5 Arsenic concentration (ppb) leached from Noranda mine tailings according
to weight percentage of nanoscale ZnO and regular ZnO after 24 hours. ................................................ 52
Figure 4-6 Arsenic concentration (ppb) leached from Golden Giant mine tailings according to
weight percentage of nanoscale ZnO and regular ZnO after 24 hours. ..................................................... 52
Figure 4-7 Arsenic concentration (ppb) leached from Noranda mine tailings according to weight
percentage of nanoscale Fe O and regular Fe O after 24 hours. ............................................................. 53
3 4 3 4
Figure 4-8 Arsenic concentration (ppb) leached from Golden Giant mine tailings according to
weight percentage of nanoscale Fe O and regular Fe O after 24 hours. ................................................. 53
3 4 3 4
Figure 4-9 Arsenic concentration (ppb) leached from Noranda mine tailings according to weight
percentage of nanoscale and regular ZnO after 30 days. ........................................................................... 55
Figure 4-10 Arsenic concentration (ppb) leached from Golden Giant mine tailings according to
weight percentage of nanoscale ZnO and regular ZnO after 30 days. ....................................................... 56
Figure 4-13 Effect of weight percentage of ZnO on water soluble arsenic fraction in Noranda
mine tailings in SSE tests. ............................................................................................................................ 62
Figure 4-14 Effect of weight percentage of ZnO on exchangeable arsenic fraction in Noranda
mine tailings following SSE tests. ................................................................................................................ 63
Figure 4-15 Effect of weight percentage of ZnO on carbonate bound arsenic fraction in Noranda
tailings following SSE tests. ........................................................................................................................ 63
Figure 4-16 Effect of weight percentage of ZnO on oxide/hydroxide arsenic fraction in Noranda
mine tailings following SSE tests. ................................................................................................................ 64
Figure 4-17 Effect of weight percentage of ZnO on sulphide/organic matter arsenic fraction in
Noranda mine tailings following SSE tests. ................................................................................................. 64
Figure 4-18 Effect of weight percentage of ZnO on the residual fraction in Noranda mine tailings
following SSE tests. ..................................................................................................................................... 65
Figure 4-19 Effect of weight percentage of ZnO on the water soluble arsenic fraction in Golden
Giant mine tailings following SSE tests. ...................................................................................................... 66
Figure 4-20 Effect of weight percentage of ZnO on the exchangeable arsenic fraction in Golden
Giant mine tailings following SSE tests. ...................................................................................................... 67
viii
Figure 4-21 Effect of weight percentage of ZnO on the carbonate arsenic fraction in Golden
Giant mine tailings following SSE tests. ...................................................................................................... 67
Figure 4-22 Effect of weight percentage of ZnO on the oxide/hydroxide arsenic fraction in
Golden Giant mine tailings following SSE tests. ......................................................................................... 68
Figure 4-23 Effect of weight percentage of ZnO on the organic matter/sulfide arsenic fraction in
Golden Giant mine tailings following SSE tests. ......................................................................................... 68
Figure 4-24 Effect of weight percentage of ZnO on the residual arsenic fraction in Golden Giant
mine tailings following SSE tests. ................................................................................................................ 69
Figure 4-25 Effect of weight percentage of Fe O on water soluble arsenic fraction in Noranda
3 4
mine tailings as shown by SSE tests. ........................................................................................................... 70
Figure 4-26 Effect of weight percentage of Fe O on exchangeable arsenic fraction in Noranda
3 4
mine tailings shown by SSE tests. ............................................................................................................... 71
Figure 4-27 Effect of weight percentage of Fe O on carbonate fraction of arsenic in Noranda
3 4
mine tailings shown by SSE tests. ............................................................................................................... 71
Figure 4-28 Effect of weight percentage of Fe O on oxide/hydroxide arsenic fraction in Noranda
3 4
mine tailings shown by SSE tests. ............................................................................................................... 72
Figure 4-30: Effect of weight percentage of Fe O on the residual arsenic fraction in Noranda
3 4
mine tailings shown by SSE tests. ............................................................................................................... 73
Figure 4-31 Effect of weight percentage of Fe O on the water soluble fraction of arsenic in
3 4
Golden Giant mine tailings shown by SSE tests. ......................................................................................... 74
Figure 4-32 Effect of weight percentage of Fe O on the exchangeable fraction of arsenic in
3 4
Golden Giant mine tailings shown by SSE tests. ......................................................................................... 74
Figure 4-33 Effect of weight percentage of Fe O on the carbonate fraction of arsenic in Golden
3 4
Giant mine tailings shown by SSE tests....................................................................................................... 75
Figure 4-34 Effect of weight percentage of Fe O on the oxide/hydroxide fraction of arsenic in
3 4
Golden Giant mine tailings shown by SSE tests. ......................................................................................... 75
Figure 4-35 Effect of weight percentage of Fe O on the organic matter/sulphide fraction of
3 4
arsenic in Golden Giant mine tailings shown by SSE tests. ......................................................................... 76
Figure 4-36 Effect of weight percentage of Fe O on the residual fraction of arsenic in Golden
3 4
Giant mine tailings shown by SSE tests....................................................................................................... 76
Figure 4-37 Distribution of phases in untreated Noranda tailings ............................................................. 77
Figure 4-38 Distribution of phases in Noranda tailings treated with 7.5% in weight of ZnO
additives ...................................................................................................................................................... 78
Figure 4-39 Distribution of phases in untreated Golden Giant tailings ..................................................... 78
Figure 4-40 Distribution of phases in Golden Giant tailings treated by 7.5% in weight of ZnO
additives ...................................................................................................................................................... 79

ix
LIST OF TABLES
Table 2-1 Arsenic contamination around the world in groundwater and coal and different
populations at risk around the world ........................................................................................................... 6
Table 2-2 Arsenic concentrations in several mine tailings ......................................................................... 10
Table 2-3 Comparison of different remediation methods ......................................................................... 17
Table 3-1 Mine tailings characterized by the XRF device ........................................................................... 28
Table 3-2 Summary of the first leaching test conducted using 5 metal oxides at a 10% weight
ratio immobilized for a period of 24h. ........................................................................................................ 31
Table 3-3 Summary of second leaching test conducted using a metal oxide at different weight
ratios immobilized for a period of 24h ....................................................................................................... 32
Table 3-4 Nanoscale Metal Oxides and their properties ............................................................................ 33
Table 3-5 Adapted SSE procedure .............................................................................................................. 34
Table 3-6 Fourteen different samples created by varying one additive weight and the type of
mine tailing. ................................................................................................................................................ 36
Table 3-7 Arsenic Test Kit Types and Measurement Ranges ...................................................................... 38
Table 3-8 Some elements for which the ICP-MS method is applicable ...................................................... 39
Table 3-9 Detection Limits for various metals analysed by ICP-MS ........................................................... 40
Table 4-1 XRF analysis results for mine tailings .......................................................................................... 44
Table 4-2 Concentration of zinc and pH of solution following the addition of ZnO additives at
different weights after 24 hours. Tailings were mixed with distilled water combined with
sulphuric acid at pH 3. ................................................................................................................................ 58
Table 4-3 Decrease in the different chemical fractions of arsenic in Noranda mine tailings after
the addition of 7.5% wt / wt ZnO................................................................................................................ 61
Table 4-4 Decrease in the different chemical fractions of arsenic in Noranda mine tailings after
the addition of 7.5% wt/ wt of nanoscale Fe O ......................................................................................... 70
3 4
Table 4-5 Particle size analysis of nanoscale ZnO and commercial grade ZnO .......................................... 80
Table 4-6 Percentage of arsenic concentration in leachate following immobilization of mine
tailings with different weights of ZnO additives. Results are compared to the mine tailings with
no additives. ................................................................................................................................................ 84

x